Interconnect technologies are widely used for packaging electrical devices. Conventional interconnect technologies include use of Z-axis tapes, wire bondings, and ball grid arrays (BGAs) as well as other solid solder interconnects. As packing density of electrical devices increases, however, conventional interconnect technologies may face reliability and cost challenges For example, when Z-axis tapes are used as interconnects, they may become unreliable in high temperature operation as occurs in solid ink print heads. When wire bonding interconnects are used, because the wire loop must be short, it is difficult to interconnect tightly packed 2-D electrical device arrays. In another example for BGAs or other solid solder interconnects, although they are capable of interconnecting small devices, thermal stress may break the connections for device arrays spanning over large distances.
In addition to the reliability and cost challenges, conventional interconnect technologies may have some other drawbacks. For example, a typical electrical device package may include an electrical device array interconnected with a flexible (or flex) circuit. The flex circuit often includes contact pads and external contacts (e.g., contact leads) and is often placed over the device array. When packaging a high density array of devices (e.g., >1000 devices per square inch), the overlaid flexible circuit has to provide contact leads very close to the contact pads for each electrical device of the array. This makes electrical interconnect between the devices and the flex circuit more challenging. For example, a Z-axis conductive adhesive film may create connection between the contact pads of the flex circuit and the devices, and may also undesirably connect other contact leads to the same electrical device of the array.
Thus, there is a need to overcome these and other problems of the prior art and to provide interconnects and methods for interconnecting tightly packed electrical device array with a flex circuit.